When a transmitter transmits a signal to a receiver, the transmission might travel over more than one path to the receiver due to diffraction and/or reflection off of objects in the surrounding environment. The signal travelling over the longest path will arrive at the receiver after the signal travelling over the shortest path. This delay is known as channel delay spread. If the channel delay spread is not accounted for, then there may be ISI (Inter-Symbol Interference) between consecutive symbols, which can make it difficult or even impossible to recover the data at the receiver.